Statistical Optimization for Tannase Production by Mucor circinelloides Isolate F6-3-12 under Submerged and Solid State Fermentation

Mucor circinelloides isolate F6-3-12 was selected out of three fungal isolates that can utilize tannic acid as substrate. The fungus was identified by phenotypic analysis and 18S rRNA gene sequencing. Extracellular tannase was produced by solid-state fermentation (SSF) and submerged fermentation (SmF) from plants known for their high tannin content to be used as sole carbon source and supporting solid substrate namely pomegranate rind, sumac leaves and green tea leaves powder, pomegranate rind was selected for maximum tannase production under SSF. Optimization using sequential statistical strategy for some vital factors; substrate concentration, temperature, substrate: moisture ratio, incubation period, inoculum age and KH2PO4 were adjusted by the sequential two design of response surface methodology. Mucor circinelloides isolate F6-3-12 produced the highest tannase level (2.07 IU) during the first 72 h of fermentaton using pomegranate rind concentration of 1 g/flask in SSF then decline after 96 h. Tannase production was enhanced from 2.07 IU to 5.83 U/gds using Plackett-Burman design and improvement up to 12.24 U/gds upon applying the Box-Behken design that considered 2.82 and 2.1 fold enhancement.